DragonFly On-Line Manual Pages

STRCPY(3)	      DragonFly Library Functions Manual	     STRCPY(3)

NAME
     strcpy, strncpy -- copy strings

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <string.h>

     char *
     stpcpy(char *dst, const char *src);

     char *
     stpncpy(char * restrict dst, const char * restrict src, size_t len);

     char *
     strcpy(char * restrict dst, const char * restrict src);

     char *
     strncpy(char * restrict dst, const char * restrict src, size_t len);

DESCRIPTION
     The stpcpy() and strcpy() functions copy the string src to dst (including
     the terminating `\0' character.)

     The stpncpy() and strncpy() functions copy at most len characters from
     src into dst.  If src is less than len characters long, the remainder of
     dst is filled with `\0' characters.  Otherwise, dst is not terminated.

RETURN VALUES
     The strcpy() and strncpy() functions return dst.  The stpcpy() and
     stpncpy() functions return a pointer to the terminating `\0' character of
     dst.  If stpncpy() does not null-terminate dst because the length of src
     was greater than len, then it returns a pointer to dst[len], which may
     not be valid.

EXAMPLES
     The following sets chararray to ``abc\0\0\0'':

	   char chararray[6];

	   (void)strncpy(chararray, "abc", sizeof(chararray));

     The following sets chararray to ``abcdef'':

	   char chararray[6];

	   (void)strncpy(chararray, "abcdefgh", sizeof(chararray));

     Note that it does not NUL terminate chararray because the length of the
     source string is greater than or equal to the length argument.

     The following copies as many characters from input to buf as will fit and
     NUL terminates the result.  Because strncpy() does not guarantee to NUL
     terminate the string itself, this must be done explicitly.

	   char buf[1024];

	   (void)strncpy(buf, input, sizeof(buf) - 1);
	   buf[sizeof(buf) - 1] = '\0';

     This could be better achieved using strlcpy(3), as shown in the following
     example:

	   (void)strlcpy(buf, input, sizeof(buf));

     Note that because strlcpy(3) is not defined in any standards, it should
     only be used when portability is not a concern.

SECURITY CONSIDERATIONS
     The strcpy() function is easily misused in a manner which enables mali-
     cious users to arbitrarily change a running program's functionality
     through a buffer overflow attack.	(See the FSA and EXAMPLES.)

SEE ALSO
     bcopy(3), memccpy(3), memcpy(3), memmove(3), strlcpy(3)

STANDARDS
     The strcpy() and strncpy() functions conform to ISO/IEC 9899:1990
     (``ISO C90'').  The stpcpy() and stpncpy() functions conform to IEEE Std
     1003.1-2008 (``POSIX.1'').

HISTORY
     The stpcpy() function first appeared in FreeBSD 4.4, coming from
     1998-vintage Linux and stpncpy() first appeared in DragonFly 2.13.

DragonFly 3.5		       January 20, 2012 		 DragonFly 3.5